| Abstract Title: | Dissolved gaseous mercury (DGM) in the Gulf of Trieste, northern Adriatic Sea |
| Presenter Name: | Jože Kotnik |
| Company/Institution: | Jožef Stefan Institute |
| Session: | Mercury in Marine Ecosystems |
| Co-Authors: | Jože Kotnik,Dušan Žagar,Gorazd Novak,Matjaž Ličer,Jadran Faganeli,Milena Horvat |
Abstract Information :
Continuous dissolved gaseous mercury (DGM) measurements were performed during the summer months (May to September 2019) in the Gulf of Trieste (northern Adriatic Sea), a well-studied contaminated site due to releases of mercury from the former mercury mine Idrija in Slovenia. Continuous DGM data were regularly checked by the discrete manual method to assure traceability and comparability of the results and used for the calculation of the upward flux of Hg (0) between the water and the air compartment, using the gas exchange model applied in previous studies in the Mediterranean Sea. The diurnal DGM variability across the entire sampling period was examined by sorting the DGM concentrations in 24 1-hour intervals. Various environmental parameters measured at oceanographic buoy Vida and the nearby stations were used to determine the correlation between DGM and the individual environmental parameters, applying simple statistical methods. The correlation with the oxygen concentration and oxygen saturation was also pronounced during the July high DGM event, and the gradient between the bottom and surface temperature was correlated with both DGM peaks in June and July. Transport from more polluted northern part of the Gulf was determined as the most probable source of both high DGM events. Other observed parameters showed no statistically significant relations with DGM. The computed annual Hg(0) flux across the water-air interface was lower than those reported in recent studies. We assume that this is due to the location of the less affected and therefore less representative sampling station of the Gulf, suggesting that for an appropriate assessment of the Hg evasion flux and of the temporal DGM variability in the polluted such heterogeneously polluted coastal areas, both spatial and temporal coverage are required.
